In this project the Matrix Assisted Laser Desorption Ionization Mass Spectrometry (MALDI) concept is being extended for use in Time-of-Flight Static Secondary Ion Mass Spectrometry (ToF-SSIMS). The overall aim of the project is to use MALDI matrix molecules to increase both the ion yields of intact proteins and peptides and to reduce fragmentation caused by Cs+ ion beam impact that occurs in standard SIMS analysis. Initial work is directed towards the detection of intact model peptide molecules. Model peptides with ?-sheet (YGLKLKLKL-NH2 Mw=1075.42 amu) and ?-helix (YG(LKKLLKL)2-NH2 Mw=1911.34 amu)) tertiary structures (synthesized using standard FMOC solid phase synthesis) are being used in conjunction with standard MALDI matrices [2,5-dihydroxybenzoic acid (DHB) and 3,5-dimethoxy-4-hydroxycinnamic (sinapinic acid (SA))] to facilitate generation of molecular ions upon irradiation with the SIMS Cs+ ion >source. SIMS imaging with micrometer spatial resolution of mat rix/peptid es crystals on Si wafers has to date suggested that this mode of analysis can be applied to specifically map the distribution of peptide molecules within MALDI crystals.